Question 756590
Given only this:  {{{3n2 + 7N =16}}}


Is this a system?  No, not really.  A system is commonly thought to be more than one equation or inequality in which all the variables are related to a situation.


"this is my question, {{{3n2 + 7N = 16}}}"
What question?  That is merely an equation.  To be perfectly logical, your equation has TWO variables, not just one variable.  Usually, {{{n<>N}}}.  If you mean these to be the same, then decide which case-level you want and use it.  


You have a character, "2" sitting on the right hand side of the first term, which you likely did not mean as a factor, but probably meant as an exponent, so you may want to show, {{{3n^2+7N=16}}}.


Please clarify what you want?


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In case you wanted to express a quadratic equation, and the variables are supposed to be the same, say {{{p=n=N}}}, then you could have {{{3p^2+7p=16}}}
{{{3p^2+7p-16=0}}}
Attempts at factoring do not seem to work, so use solution to quadratic formula:
{{{highlight(p=(-7+- sqrt(241))/6)}}}